Pre-infection of pigs with Mycoplasma hyopneumoniae modifies outcomes of infection with European swine influenza virus of H1N1, but not H1N2, subtype

Abstract

Swine influenza virus (SIV) and Mycoplasma hyopneumoniae (Mhp) are widespread in farms and are major pathogens involved in the porcine respiratory disease complex (PRDC). The aim of this experiment was to compare the pathogenicity of European avian-like swine H1N1 and European human-like reassortant swine H1N2 viruses in naïve pigs and in pigs previously infected with Mhp. Six groups of SPF pigs were inoculated intra-tracheally with either Mhp, or H1N1, or H1N2 or Mhp+H1N1 or Mhp+H1N2, both pathogens being inoculated at 21 days intervals in these two last groups. A mock-infected group was included. Although both SIV strains induced clinical signs when singly inoculated, results indicated that the H1N2 SIV was more pathogenic than the H1N1 virus, with an earlier shedding and a greater spread in lungs. Initial infection with Mhp before SIV inoculation increased flu clinical signs and pathogenesis (hyperthermia, loss of appetite, pneumonia lesions) due to the H1N1 virus but did not modify significantly outcomes of H1N2 infection. Thus, Mhp and SIV H1N1 appeared to act synergistically, whereas Mhp and SIV H1N2 would compete, as H1N2 infection led to the elimination of Mhp in lung diaphragmatic lobes. In conclusion, SIV would be a risk factor for the severity of respiratory disorders when associated with Mhp, depending on the viral subtype involved. This experimental model of coinfection with Mhp and avian-like swine H1N1 is a relevant tool for studying the pathogenesis of SIV-associated PRDC and testing intervention strategies for the control of the disease.

Effect of Feed Restriction on Performance and Postprandial Nutrient Metabolism in Pigs Co-Infected with Mycoplasma hyopneumoniae and Swine Influenza Virus

“…This was in agreement with the symptoms we observed in similar previous studies [17], [18]. In the present experiment, we showed that feed restriction induced a decrease in rectal temperature that could be caused by a decrease in heat production due to feed digestion [26].…”

“…Strain isolations, as well as preparation and titration of inocula were performed as previously described [17].…”

Update onMycoplasma hyopneumoniaeinfections in pigs: Knowledge gaps for improved disease control

“…Deblanc et al. () showed that M. hyopneumoniae infection increased the severity of H1N1 SIV but not that of H1N2 SIV. Opriessnig et al.…”

Co-infection of classic swine H1N1 influenza virus in pigs persistently infected with porcine rubulavirus

“…Viruses that cause respiratory disease and pneumonia in growing pigs include the porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), pseudorabies virus (PRV), porcine rubulavirus (PorPV), porcine circovirus type-2 (PCV-2), and porcine respiratory coronavirus (PRCV). All these viral agents can act individually or through interaction with each other, and associations with other infectious agents of bacterial origin can also occur (Choi et al, 2003;Deblanc et al, 2012;Grau-Roma and Segales, 2007;Kirkland and Stephano, 2006;Morin et al, 1990;Rivera-Benitez et al, 2013a;Segales et al, 1997). PorPV is the etiological agent of blue-eye disease (BED) in pigs.…”

“…The common subtypes circulating in swine have been characterised as H1N1, H1N2, and H3N2 (Brookes et al, 2009;Olsen et al, 2006). SIV has been associated with porcine respiratory disease complex (PRDC) in growing or fattening pigs (10-22 weeks of age), while interactions with Mycoplasma hyopneumoniae, PRRS, and PCV-2 (Deblanc et al, 2012;Van Reeth et al, 1996Yazawa et al, 2004 have been widely studied. There are no previous studies of experimental or natural co-infection of PorPV and SIV.…”